Photosensitive flexographic printing plates are becoming more important in the printing trade. Particularly useful compositions for preparing such flexographic printing plates contain butadiene/acrylonitrile polymers with optional carboxyl groups, addition polymerizable ethylenically unsaturated compounds, and photoinitiators. The composition is formed into a layer and is generally laminated to a flexible support. It has been found that the adhesion of the photosensitive layer to the support is inadequate unless an adhesive composition is used to bond the layer to the support. Proskow U.S. Pat. No. 4,177,074 which relates to photosensitive, flexographic layers, discloses in column 9, line 10 to 16, that known adhesive compositions can be used to give strong adherence. Other known adhesives are those of the polyester type which can be used with curing agents such as isocyanates. These adhesives, while providing improved bonding between the photosensitive layer and the support, are not up to the desired standard under all conditions. The polyester adhesive containing the isocyanate curing agent must be brought into contact with the photosensitive layer almost immediately after preparation or an inferior bond will result due to premature curing of this adhesive. Adhesive blends are known to be useful in printing plates to bond the photosensitive layer to the support. It is not known, however, that adhesive blends have been used previously in flexographic printing plates.
It is an object of this invention that a photosensitive flexographic element be provided that possesses excellent adhesion between the photosensitive layer and the support. Another object is to provide such adhesion at normal ambient conditions using an adhesive blend without the necessity of a curing step.